The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Computer networks typically are comprised of multiple network elements, such as routers, that communicate data to each other. Working together or individually, network elements may provide various services. For example, several routers working together may provide a voice-over-IP service.
The quality of network elements or services may be measured according to various metrics. One metric used to measure the quality of network elements and services is the availability metric. To simplify the discussion below, availability is discussed in the context of network elements. However, the following references to the availability of network elements apply equivalently any other kind of computing element, and to services.
At least in theory, a network element's availability with respect to a given time period should reflect the fraction of that time period that the network element was at least partially operational. The availability metric theoretically could be used for many different purposes. For example, if obtained accurately, the availability metric might be used to perform availability-based routing. Given multiple network routes between a specified source and a specified destination, availability-based routing would seek to determine and use the route that contains network elements having the highest aggregate availability.
Unfortunately, current approaches for measuring availability do not lend themselves well to practical use. This is largely because such current approaches usually approximate only the availability of types of network elements generally. In the real world, the actual availability of a specific network element can vary greatly from the availability approximated relative to that network element's type. The inaccuracy resulting from current approaches disables practical applications that require greater precision, such as, for example, availability-based routing.